I have an M3 rep bumper arriving tomorrow and have some big plans for it (thank you whoever bumped my car in the parking lot, I wasn't expecting to get one so soon). While I don't care about retaining the brake cooling ducts because I don't race, and when you are going straight they just blow onto your tire anyway, I DO care about retaining the oil cooler duct.

I will be doing the fog delete, and I have these sitting on my dining room table now (51747900823/824):

I knew the larger one should bolt right up to the oil cooler (not sure if I keep the partial block-off plate that is on it), but was unsure where the driver's side duct ended up. ECS Tuning listed it as a brake duct, but the upward angle suggested otherwise. I did some digging and found out it is one of 3 inlets to the M3 intake box!

Since the filter for my intake sits behind the bumper sandwiched between the fog light and wheel well, I plan to use this duct as a cold air supply. An added bonus for me! And since the duct is designed for an intake, it has several bends and ridges to ward off water. I wont be hooking it up directly to the filter, but it should provide a large volume of fresh cool air to that otherwise hot cramped cavity

Saw these. I was about to buy one and then I saw it was only 1 inch tall. I am not sure if this is sufficient enough for me to clamp down the rubber boot. So instead, I ordered one of these from Amazon:

My plan is to remove the rubber hole plug and cover the hole on the side with 2 layers of aluminium ducting tape. Then trim any material from the flange portion till it fits. Order should be coming some time next week and I'll probably revise my DIY Hybrid Intake article.

Well, that didn't work LOL... I attempted to get the M3 ducts to fit and just couldn't get them in there. They fit the bumper perfectly, but did not fit in the space between the bumper and wheel well cover. I trimmed and trimmed, but got to the point where using them would be pointless. I ended up taking them off and just going duct and fog -free. This setup should work very well, as there is plenty of air going to the oil cooler cavity and a direct flow to the air filter. I was mildly concerned about rain and puddles hitting the filter, but after thinking about it I don't think it will be an issue. The pre-filter I have is nylon-ish mesh and repels water. Also, the design of the system allows the air to take the path of least resistance, so if I somehow submerge the filter, the OEM intake path will take over. I am very happy with the setup overall, and my FMIC now has full exposure as well (the OEM bumper blocked a good 50% of the fin area).

With drawing from multiple air sources I don't think you could create enough vacuum on that path to get more than a decent mist with the filter getting completely soaked. The pre filter does an excellent job of repelling water, I used them on my ATV's and even with water rolling around in the air box I never had a hiccup.

Yeah, no complaints thus far... been working out quite well. In the summer I'll keep the filter right at the opening, but in heavy rains and through the winter I'll tuck it up into the bumper. It keeps it out of harms way, away from road chemicals, and at the most gets a light mist from back-splash. I need to give it a good cleaning soon but other than that the setup is working great.